U.S. patent number 4,252,501 [Application Number 05/524,478] was granted by the patent office on 1981-02-24 for hollow cooled vane for a gas turbine engine.
This patent grant is currently assigned to Rolls-Royce Limited. Invention is credited to Peter G. Peill.
United States Patent |
4,252,501 |
Peill |
February 24, 1981 |
Hollow cooled vane for a gas turbine engine
Abstract
A hollow cooled vane for a gas turbine engine comprises at least
two apertured members each mounted spaced from a separate part of
the vane interior surface. The first of these members is provided
with a supply of cooling air which passes through the apertures in
the form of jets to impingement cool the respective first surface,
and an interconnecting passage is provided to take this air to the
second apertured member where it impingement cools the respective
second surface.
Inventors: |
Peill; Peter G. (Hamilton,
CA) |
Assignee: |
Rolls-Royce Limited (London,
GB2)
|
Family
ID: |
10466157 |
Appl.
No.: |
05/524,478 |
Filed: |
November 14, 1974 |
Foreign Application Priority Data
|
|
|
|
|
Nov 15, 1973 [GB] |
|
|
52985/73 |
|
Current U.S.
Class: |
415/115; 416/96A;
416/97R |
Current CPC
Class: |
F01D
5/189 (20130101); F01D 9/065 (20130101); F05D
2240/81 (20130101); F05D 2260/201 (20130101) |
Current International
Class: |
F01D
5/18 (20060101); F01D 005/18 () |
Field of
Search: |
;415/115,116
;416/90,95,96,232,233,96R,96A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Bentley; Stephen C.
Attorney, Agent or Firm: Cushman, Darby & Cushman
Claims
I claim:
1. A hollow cooled vane for a gas turbine engine comprising at
least two apertured members each supported spaced from a separate
part of the vane interior surface, the first of said apertured
members being adpated to be fed with cooling air from the exterior
of the vane, the apertures in said member allowing the air to flow
through it in the form of jets which impinge on and cool the
respective first part of the vane interior surface, and
interconnecting passage means being provided to cause the air which
has impinged on said first part of the vane interior surface to
flow to said second apertured member and to flow through the
apertures therein in the form of jets which impinge on and cool the
respective second part of the vane interior surface.
2. A hollow cooled vane as claimed in claim 1 and in which said
first and second apertured members comprise air entry tubes.
3. A hollow cooled vane as claimed in claim 2 and in which the vane
has a hollow aerofoil section, said air entry tubes being located
in the forward and rearward portions of the hollow aerofoil section
of the vane.
4. A hollow cooled vane as claimed in claim 3 and in which there is
an apertured web which divides the interior of the hollow aerofoil
section of the vane into said forward and rearward portions, the
apertures in the web being aligned with and sealed to corresponding
apertures in the second air entry tube and comprising said
interconnecting passage.
5. A hollow cooled vane as claimed in claim 3 and in which the
forward air entry tube comprises a part tube sealed to the forward
portion of the vane interior so that this portion completes the
tube, said forward portion being provided with drillings through
which cooling air may flow to film cool part of the exterior
surface of the blade.
6. A hollow cooled vane as claimed in claim 3 and in which the
second air entry tube is divided into two longitudinally extending
parts, one of which is fed with cooling air after it has impinged
on said first part of the vane interior surface and the second of
which is fed directly with cooling air from the exterior of the
vane.
7. A hollow cooled vane as claimed in claim 1 and in which said
vane comprises a shroud having a surface away from the gas flow of
the engine, and said first apertured member comprises an
impingement cooling plate mounted spaced from said surface.
8. A hollow cooled vane as claimed in claim 7 and in which said
second apertured member comprises an air entry tube.
9. A hollow cooled vane as claimed in claim 8 and comprising a
hollow aerofoil section whose interior is divided into separate
forward and rearward portions, one air entry tube being mounted in
each of said portions and said second apertured member being the
rearmost one of said tubes.
10. A hollow cooled vane as claimed in claim 9 and in which the air
entry tube mounted in the forward compartment is provided with a
direct feed of cooling air from the exterior of the vane.
11. A hollow cooled vane as claimed in claim 9 and in which said
rearmost air entry tube projects into the space between the
impingement plate and the shroud so as to obtain its supply of
cooling air.
Description
This invention relates to a hollow cooled vane for a gas turbine
engine.
Throughout this specification the term `vane` is to be understood
to include within its scope stator blades, aerodynamic struts, and
rotor blades, all for use in turbines or compressors or other parts
of the engine.
In gas turbine engines it is common to manufacture various of the
parts, particularly the turbine vanes and blades, so that they may
be cooled by the flow of a cooling fluid, normally air, through and
within their hollow interiors. The use of this cooling fluid
represents a penalty which subtracts from the thrust available from
the engine; consequently it is important that the cooling fluid be
used in as efficient a manner as possible.
One known way of cooling the hollow vanes is to cause the cooling
fluid to flow through apertures in a member in the form of jets
which impinge on an interior surface of the blade; this
`impingement` cooling provides an efficient use of cooling fluid
particularly in those areas where the temperature is somewhat less
than the highest to be experienced. The present invention provides
a way in which a single flow of cooling fluid may be used to
provide sequential impingement cooling of two areas of the
vane.
Throughout this specification references to an interior surface of
the vane are to be understood to include all those surfaces of the
vane not exposed to the gas flow of the engine, and specifically
includes the surfaces of the shrouds and/or platforms of the vane
remote from the gas flow of the engine.
According to the present invention a hollow cooled vane for a gas
turbine engine comprises at least two apertured members each
supported spaced from a separate part of the vane interior surface,
the first of said apertured members being adapted to be fed with
cooling air from the exterior of the vane and to cause said air to
flow through its apertures in the form of jets to impinge on and
cool the respective first part of the vane interior surface and
interconnecting passage means being provided to cause the air which
has impinged on said first part of the vane interior surface to
flow to said second apertured member and to flow through the
apertures therein in the form of jets to impinge on and cool the
respective second part of the vane interior surface.
Said first apertured member may be supported spaced from the
surface of the shroud or platform of the vane remote from the gas
flow of the engine, in which case said second apertured member may
comprise an air entry tube mounted within the hollow interior of
the aerofoil section of the blade.
Alternatively the first said apertured member may comprise an air
entry tube which may be a complete tube or may be an incomplete
tube which is completed by part of the vane wall to which it is
sealed, and the cooling fluid may be fed from outside the vane to
the interior of this tube.
Said second apertured member may comprise an apertured tube and the
sole supply of cooling fluid to the interior of the apertured tube
may be from said air entry tube.
Additional to the cooling of the vane performed by the impingement
cooling mentioned above, the vane may be provided with drillings
from its interior to its exterior surface through which cooling
fluid may flow to provide film cooling. In this case it may be
desirable to allow cooling fluid from the air entry tube direct
access to the film cooling holes adjacent the leading edge by using
that part of the vane as part of the air entry tube.
The invention will now be particularly described, merely by way of
example, with reference to the accompanying drawings in which:
FIG. 1 is a side elevation of a gas turbine engine whose casing is
partly broken-away to show vanes in accordance with the
invention,
FIG. 2 is an enlarged side view, partly broken away, of the vane of
FIG. 1,
FIG. 3 is a section on the line 2--2 of FIG. 2, showing the section
of a vane,
FIG. 4 is a view similar to FIG. 2 but of a further embodiment,
FIG. 5 is a section on the line 5--5 of FIG. 4, and
FIG. 6 is a section on the line 6--6 of FIG. 4.
In FIG. 1 there is shown a gas turbine engine comprising a casing
10 which encloses a compressor 11, combustion section 12, turbine
13 and final nozzle 14 all in flow series. The casing at the
downstream end of the combustion section is broken away to make
visible the combustion chamber 15 and the nozzle guide vanes 16
which direct gases from the chamber on to the rotor blades 17 of
the turbine. FIG. 2 shows one of the vanes 16 enlarged and partly
broken away to show some detail of the interior. It will be seen
that the vane comprises an aerofoil section working portion which
is formed integrally with inner and outer shroud portions 18 and 19
respectively. The outer shroud portion 19 is provided with an
aperture 20 in its leading section to which a supply of compressed
cooling air is provided from the compressor section 11.
Within and sealed to the periphery of the aperture 20 fits a
cooling air entry tube 21; this tube extends longitudinally through
the vane and is sealed at its inner end to the inner shroud 18. As
can best be seen from FIG. 3, although the tube 21 is described as
a tube, it is not in fact a complete tube but comprises a
U-section, the limbs of which are sealed and retained into grooves
in ridges 22 which extend longitudinally from the blade interior
surface adjacent the leading section of the blade. The U-section of
the tube 21 is thus completed by the area of the leading edge
between the ridges 22 to form a complete tube.
The remaining section of the tube comprises the limb portions of
the U-section which are substantially constantly spaced from the
flank parts adjacent the leading edge, and a rear section. The limb
portions are apertured to allow air to flow from the interior of
the tube to impinge on the inner surfaces of the blade, while the
leading edge portion of the blade between the ridges 22 is provided
with film cooling holes which allow cooling air to flow to the
outer surface of the vane to provide film cooling.
The forward section of the vane in which is housed the tube 21 is
separated from the rearward section by an apertured web 23, the
apertures of which correspond with the apertures 24 in the
forwardly facing surface of a second tube 25. This tube conforms to
the interior shape of the trailing edge section of the vane and is
mounted so as to have its outer surface substantially constantly
spaced from the inner vane surface by springy tubes 26, 27 and 28.
These tubes extend longitudinally of the vane and provide sealing
between the tube and the vane as well as locating the tube inside
the vane, although it may be desirable to provide further location
features.
In addition to the apertures 24 the tube 25 is provided with
apertures 29 and 30 in those walls of the tube which extend
adjacent the convex and concave flanks of the vane respectively. In
this particular embodiment a partition 31 is also provided within
the tube 25, sealing that section of the tube which supplies air to
the apertures 29 from that section which supplies air to the
apertures 30. As can best be seen from FIG. 2, that section of the
tube 25 which supplies air to the apertures 30 is provided with a
direct feed of cooling air from outside the outer shroud 19. Thus
the half-tube formed between the partition 31 and the wall of the
tube 25 which provided with apertures 30 is arranged to project
through the shroud 19 to take up cooling air directly. The other
end of the tube is sealed to the inner shroud portion 18.
Once again, film cooling holes are provided in both concave and
convex flanks of the trailing edge portion of the vane so that film
cooling of this portion may also be effected; these holes are not
enumerated since they are not central to the present invention.
At the trailing edge itself of the vane there is provided an air
exhaust slot which extends completely along the trailing edge of
the vane and through which any remaining cooling air exhausts to
atmosphere.
Operation of the cooling system of the vane is as follows: cooling
air from the compressor enters the tube 21 and flows down it,
exhausting via the film cooling holes in the leading edge section
between the ribs 22 and via the sets of apertures in the tube
itself. The air which exhausts from the film cooling holes provides
film cooling of the leading edge in the normal manner; it will be
noted that these holes have direct access to the air as soon as it
enters the vane and thus the best use is made of the pressure
available to film cool at the leading edge, where the ambient gas
pressure is at its highest.
Air flowing through the apertures in the tube is caused by the size
and disposition of the apertures to flow in the form of jets which
impinge on the inner surface of the vane to provide impingement
cooling; this air although reduced in pressure by its passage
through the apertures is of sufficient pressure to flow through the
film cooling holes in the adjacent portions of the vane to provide
film cooling. Only a small proportion of the available air is used
to provide film cooling, the remainder flowing between the tube and
the vane interior through the apertures in the web 23 and through
apertures 24 into the tube 25. Here the air passes through
apertures 29 to impinge on and thus cool the trailing edge part of
the convex flank of the vane. A separate intake of cooling air
through the outer shroud 19 flows through the apertures 39 to
impingement cool the trailing edge part of the concave flank of the
vane. As in the case of the leading edge, air flows through film
cooling holes to provide additional film cooling of the surfaces.
In the case of the air flowing through apertures 30 the seals
formed by the resilient tubes 27 and 28 prevent the air from
escaping from the space between the vane and the tube 25 by any
route other than through the film cooling holes; consequently the
complete flow through the apertures 30 exhausts through the film
cooling holes, and the pressure of this air may be arranged to be
different from that which exhausts through the trailing edge.
The air which passes through the apertures 20 on the opposite side
of the vane, however, can flow between the tube 25 and vane
interior surface to the rear of the vane and can escape through the
trailing edge slot 32; thus only a proportion of the air which
passes through the apertures 29 passes through the film cooling
holes to film cool the trailing portion of the convex flank.
FIGS. 4-6 show a further embodiment in which the two locations at
which impingement cooling is successively provided by the same flow
of air, are located one on the inner shroud of the blade and one
inside the hollow interior of the aerofoil.
It will be seen that the vane is externally similar to that of the
previous embodiment, comprising an inner shroud 40, an outer shroud
41 and an aerofoil section portion 42. The aerofoil section is
hollow and divided by a web 43 into forward and rearward
compartments 44 and 45. The forward compartment is provided with an
air entry tube 46 which extends from the surface of the shroud 41
distant from the gas flow, where it communicates with a source of
cooling air, and is blanked off at its other end adjacent the inner
shroud 40.
Rows of orifices 47, 48 and 49 are provided in the tube 46 which
allow the cooling air to flow in the form of jets against the
interior surface of the forward compartment 44 to provide
impingement cooling, and the air then flows through drillings 50,
51 and 52 to the exterior surface of the blade to provide film
cooling of the surface. Thus the cooling of the forward section of
the blade is quite conventional.
In this embodiment the inner shroud 40 is provided with cooling;
thus an impingement plate 53 is sealed to a peripheral rib 54 from
the face of the shroud away from the gas flow, and is spaced
therefrom by a constant small distance. Apertures 55 are provided
in the plate, and as in the case of the tube 46 these are sized so
that a flow of cooling air from a source not shown passes through
the apertures 54 in the form of jets which impinge on the surface
of the shroud 40 to provide impingement cooling.
The air which has impinged on the shroud surface then flows into a
rearward air entry tube 56 which is located within and
substantially conforms with the interior shape of the rearward
compartment 45 of the vane.
The tube 56 is blanked off at its end adjacent the shroud 41; as
inferred above its other end extends into and is open to the space
between the plate 53 and shroud 40 so that it can pick up the
cooling air which has impinged on the shroud surface.
The tube 56 is provided with rows of apertures 57, 58, 59 and 60
which again are sized to allow the cooling air to flow as jets
which impinge on the inner surface of the rearward compartment 45.
The spent air then flows out of the vane through trailing edge
slots 61, providing further cooling of the trailing edge.
This second embodiment, therefore, uses one flow of air to provide
impingement cooling on the shroud and in the hollow inside of the
vane, both these areas being according to our definition interior
surfaces of the vane.
It will therefore be seen that the invention enables a single flow
of cooling air to be used twice over to provide a high degree of
impingement cooling at one location and a lesser degree at a second
location, although the cooling at the two locations could be
arranged to be similar, or to be greater at the second location. It
also in the first embodiment, provides a high initial pressure and
subsequently lower pressures towards the trailing edge of the vane
which makes it easy to provide film cooling air at the correct
pressure and which uses the cooling potential of the air over the
whole blade section.
It should be noted that the constructions above are two of a number
of potential ways of applying the present invention. Instead of
using two tubes as the apertured members, other devices such as
discrete plates or webs could be used; in this way it would be
possible to successively cool two or more areas of the vane. The
construction could obviously be used for more than two areas in
succession. The cooled areas need not include the complete vane; it
would be possible to use this construction to provide cooling for
e.g. the central section of the vane, the other portions being
cooled by other methods.
Again, although described in its application to a vane the
invention could clearly be used for rotor blades or struts or other
aerofoil gas-contacting member.
* * * * *